The crystalline lens is a quite remarkable living tissue as it is able to maintain an optical transparency sufficient for the physiological needs of sight. However, this clarity may be markedly reduced (cataracts) with the use of some drugs and toxic chemicals, in certain diseases, and, as occurs most frequently, with advancing age ('senile' cataracts). The cause(s) of the latter are unknown but they may be associated with changes in the mineral content of the lens, including sodium, potassium, calcium and magnesium. In this study on the rabbit lens we wish to examine the accumulation and possible role of toxicants, especially trace metal such as copper, lead, cadmium, aluminum and mercury on lenticular mineral metabolism.